The recommendations by the Privacy and Civil Liberties Oversight Board go further than Obama is willing to accept and increase pressure on Congress to make changes.

The panel's 234-page report included dissents from two of the board's five members — former Bush administration national security lawyers who recommended that the government keep collecting the phone records.

The board described key parts of its report to Obama this month before he announced his plans last week to tweak the government's surveillance activities.

In that speech, Obama said the bulk phone collection program would continue for the time being, but he directed the Justice Department and intelligence officials to find ways to end the government's control over the phone data.

He also insisted on close supervision by a secretive federal intelligence court and reducing the breadth of phone records the NSA can investigate.

Besides concluding that the daily collection of phone records was illegal, the board also determined that the practice was ineffective.

“We have not identified a single instance involving a threat to the United States in which the program made a concrete difference in the outcome of a counterterrorism investigation,” it said.